Question

“You cannot see a person standing on the other side of a boundary wall but can hear him.” Explain with reason.

Answer 1

Why You Can Hear but Not See a Person Behind a Wall

The reason you cannot see a person standing on the other side of a boundary wall but can hear them is based on the difference in the wavelengths of light and sound.

Light Waves:

Light waves have very small wavelengths, in the order of nanometers (approximately \(10^{-9}\) m). These small wavelengths cannot bend around large obstacles like walls, which are much larger than the wavelength of light. As a result, light waves cast sharp shadows, and you cannot see the person standing behind the wall.

Sound Waves:

Sound waves, on the other hand, have much longer wavelengths, typically in the order of centimeters to meters. These longer wavelengths can diffract around the edges of a boundary, such as a wall, and thus can be heard even though the person is not visible.

This phenomenon is an example of diffraction, where waves spread out and bend around obstacles.